1. Field of the Invention
The invention relates to a fuel cell. More particularly, the invention relates to an improvement in the structure of a fuel cell.
2. Description of the Related Art
A fuel cell (such as a polymer electrolyte fuel cell) is typically made by stacking together a plurality of cells each having an electrolyte sandwiched between separators. These separators are provided with ribs (gas flow path ribs) which form flow paths by dividing the area through which reaction gases (i.e., fuel gas and oxidizing gas) flow. These gas flow path ribs are generally parallel with one another, for example.
Conventionally, when a separator is provided with such ribs, ribs that divide adjacent flow paths where the reaction gas flows in opposite directions are often wider than ribs that divide adjacent flow paths where the reaction gas flows in the same direction (see Japanese Patent Application Publication No. JP-A-2001-76746, for example). This is mainly in order to inhibit the reaction gas from taking a shortcut to an adjacent flow path by seeping past the ribs, a phenomenon referred to as path cutting, and is often used in fuel cells or the like that have so-called serpentine gas flow paths.
However, even with ribs that are structured in the manner described above, it is difficult to sufficiently inhibit path cutting of the reaction gas. When such path cutting occurs and the reaction gas takes a shortcut in the course of its flow, the flow of the gases along their gas flow paths becomes disturbed which reduces the gas stoichiometry in the power generating region, thus reducing power generating performance.